Thousands of fans queued up overnight to get their hands on the latest expansion pack for World of Warcraft (WoW).
With 12 million subscribers around the world it's one of the biggest games on the market.
Cataclysm sees the World of Warcraft world ripped apart and remade.
Greg Street is the lead system designer on the game and spoke to Newsbeat's technology reporter Dan Whitworth.
Can you explain World of Warcraft in two sentences?
WoW is a role playing game and you take on the role of a character, like a warrior or a priest, and you go out to vanquish evil and become a hero.
The nice thing about WoW is that you can play online with your friends and so it's a very social game.
What is Cataclysm?
Cataclysm is our new expansion [pack].
We've gone back and we've changed a lot of the original WoW.
We've updated it for 2010 with a particular emphasis on making it accessible to new players.
Why have you changed things so much with Cataclysm?
The game is six years old now and parts of it are showing its age.
We thought we could do a lot better with the art and the design and we thought we could make it a more fun game by revisiting some of the old world.
What's it been like to work on the game?
I love my job, I love the game and I love our players.
But at the same time it's an enormous amount of responsibility and I always worry if we're going to make a mistake and make the game less fun for people.
It's a lot of pressure but overall it's a great job.
What makes WoW so popular?
I think the game has a lot of soul.
I think the love that developers have for the product really shows in the game.
The art style is very easy for players to get into and I think overall it's just fun.
What's next for fans?
After we release an expansion [pack] we follow it up with a series of big content patches where we give away a lot of material to existing players to have new dungeons, new quests and new things to do.
Then eventually we'll work on the next expansion.
Ryan Gray: Do you think this expansion will be a bigger hit than the last one and how are you going to stop players from getting bored?
We try to offer players a lot of different things to do.
We have a lot of upgraded battle grounds in Cataclysm, a lot of quests, new races for players to play.
As for whether it'll be bigger I think it's too soon to tell.
We hope it will attract a lot of new players to the game and give some players who may have put it to one side a reason to come back and check it out again.
Charlotte Falconer: Gamers like Felicia Day have helped raise the profile of female players, but what do you think girl gamers will enjoy the most about the expansion?
It's hard to stereotype about what women like compared to men.
Some female gamers I know like it because it's a very social game and they get to play it with their friends.
But I know some very hard core cut-throat female gamers who like to go out and kill each other or kill the monsters.
David-Joseph Thompson: How many content patches are we going to see during Cataclysm?
We're still debating that.
There will definitely be two or three at this point.
It kind of depends on how quickly we can do the next expansion and what kind of content makes sense for us.
Kenneth Fitzsimons: Does Blizzard not reckon the 12 million subscribers currently playing is close to saturation point?
I think the game still has plenty of opportunities to grow.
We have new players joining us all the time.
There are new places in the world that are just getting the network stability they need to play the game so we're making inroads into different parts of the world.
There's a whole generation of gamers that have grown up on consoles and once they hit the appropriate age it's something they start to look at.
Al Bretherton: I have been playing since the original beta, six years ago. There are a lot of stories to tell in Azeroth but, realistically, when does Blizzard think it will end? I heard there will be two more expansions. Can the quality be upheld for another six years?
I think we uphold the quality as long as we need to.
As far as two more expansions, I think it would be a little silly to pull a game with millions of active subscribers.
We don't view it in terms of a definite ending.
We have some ideas about what the final story could be and how it should end but I think it'll be a long time before we have to worry about that.